Output control method, circuit and radio frequency device

Abstract

The present invention discloses an output control method, a circuit and a radio frequency device. The output control method is applied to the radio frequency device, comprising: stepping down and regulating the power supply voltage of the radio frequency device in response to a first control signal to obtain an output voltage VOUT, wherein the first control signal is generated according to a preset output power and output current of the radio frequency device; sampling the output current to obtain a sampled current; generating a second control signal with an adjustable signal frequency dead time according to the sampled current; controlling a full-bridge circuit in response to the second control signal with an adjustable signal frequency dead time to fine-tune the pulse width of the output voltage VOUT to obtain an actual output; and amplifying the power of the actual output and outputting it to a load, so that the actual output power output by the radio frequency device to the load reaches the preset output power.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency therapeutic apparatus, and more specifically to an output control method, circuit and radio frequency equipment. Background Art

[0002] Radiofrequency therapeutic apparatus is a medical device that uses low-frequency electromagnetic waves to act on human diseased tissues, causing polarized water molecules in the tissues to move at high speed, generating heat (i.e., endogenous thermal effect), causing proteins to coagulate at low temperatures and lose their activity, and finally causing them to fall off through the body's rejection, thereby achieving the purpose of treatment. In the prior art, the internal output circuit of radiofrequency therapeutic apparatuses mostly uses a controller to generate a bidirectional symmetrical square wave radio frequency signal of a corresponding frequency, and then controls the output power of the radio frequency signal through a full-bridge circuit and a transformer. That is, a controller generates a bidirectional symmetrical square wave radio frequency signal of a corresponding frequency, and then the bidirectional symmetrical square wave after adjusting the dead zone size is amplified by a full-bridge circuit and a transformer to control the power of the radio frequency signal. However, because the maximum duty cycle of the bidirectional symmetrical square wave is less than 50%, the dead zone adjustment range is limited, and when the dead zone accounts for too large a proportion, the waveform will be severely deformed after amplification, resulting in a large adjustment error of the radio frequency signal power and low precision. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an output control method, circuit and radio frequency device which can adjust the output power with high adjustment accuracy.

[0004] In order to solve the above technical problems, according to one aspect of the present invention, an output control method is provided, which is applied to a radio frequency device and includes: In response to a first control signal, a power supply voltage of the radio frequency device is stepped down to obtain an output voltage VOUT, wherein the first control signal is generated according to a preset output power and output current of the radio frequency device; Sampling the output current to obtain a sampling current; Generate a second control signal with adjustable signal frequency dead time according to the sampled current; In response to a second control signal with an adjustable signal frequency dead time, the full-bridge circuit is controlled to fine-tune the pulse width of the output voltage VOUT to obtain an actual output; The actual output is power-amplified and then output to the load, so that the actual output power output by the RF device to the load reaches the preset output power.

[0005] To solve the above technical problems, according to another aspect of the present invention, an output control circuit is provided, which is applied to radio frequency equipment and includes a programmable voltage regulation circuit, a full-bridge circuit, a transformer, an isolation sampling circuit and a main control circuit; wherein, The program-controlled voltage regulating circuit is connected to the power supply of the radio frequency device, and is used to step down and regulate the power supply voltage of the radio frequency device in response to the first control signal from the main control circuit to obtain an output voltage; The full-bridge circuit is connected to the output end of the program-controlled voltage regulation circuit, and is used to control the on-time of the full-bridge circuit within one cycle in response to the second control signal with adjustable dead time of the signal frequency from the main control circuit, so as to fine-tune the pulse width of the output voltage from the program-controlled voltage regulation circuit to obtain the actual output; The transformer is connected between the output end of the full-bridge circuit and the load, and is used to amplify the actual output and output it to the load, so that the actual output power output by the radio frequency device to the load reaches the preset output power; The input end of the isolation sampling circuit is connected to the output end of the transformer, and is used to collect the output current of the secondary side of the transformer to obtain the sampling current; The main control circuit is connected to the programmable voltage regulating circuit, the full-bridge circuit and the isolated sampling circuit, and is used to output a first control signal and / or a second control signal according to a preset output power and a collected sampling current to control the operation of the programmable voltage regulating circuit and the full-bridge circuit, thereby adjusting the actual output power of the radio frequency device.

[0006] In order to solve the above technical problem, the present invention further provides a radio frequency device, which includes the above output control circuit.

[0007] Compared with the prior art, the present invention performs step-down regulation on the power supply voltage of the radio frequency device in response to the first control signal to obtain the output voltage VOUT, and samples the output current to obtain the sampled current, thereby obtaining the actual output power at this time, and generates a second control signal with an adjustable output signal frequency dead time according to the actual output power corresponding to the sampled current and the preset output power, and then controls the operation of the full-bridge circuit based on the second control signal with adjustable signal frequency dead time to fine-tune the pulse width of the output voltage VOUT obtained after the step-down regulation, and the signal frequency dead time of the second control signal is adjusted according to the difference between the actual output power and the preset output power, thereby achieving fine-tuning of the actual output power, and then the actual output obtained after the fine-tuning is power-amplified and output Output to the load, so that the output power corresponding to the actual output obtained after fine-tuning reaches the preset output power. During the entire adjustment process, the first control signal and the second control signal can generate outputs according to the preset output power and the sampling current of the RF device respectively. It can be seen that in the present invention, the power supply voltage of the RF device can be adjusted to a large extent based on the first control signal, and then the output voltage VOUT is fine-tuned by the pulse width based on the second control signal with adjustable signal frequency dead time generated by sampling the sampling current obtained after the large-scale adjustment, that is, the error between the preset output power and the actual output power is accurately repaired, then the adjustable range of the signal frequency dead time can be narrower, and the problem of serious deformation and distortion of the waveform after amplification when the dead zone accounts for too large a proportion is solved, and the adjustment accuracy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a flow chart of a specific embodiment of the output control method of the present invention; Figure 2 It is a waveform diagram of a second control signal having a bidirectional symmetrical square wave and an adjustable signal frequency dead time; Figure 3 It is a circuit block diagram of a specific embodiment of the output control circuit of the present invention; Figure 4 It is a specific circuit diagram of the program-controlled voltage regulating circuit in the output control circuit of the present invention. DETAILED DESCRIPTION

[0009] In order to enable those skilled in the art to more clearly understand the objectives, technical solutions and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0010] Reference Figure 1 , Figure 1The output control method of the present invention is applied to radio frequency equipment (such as radio frequency therapeutic equipment) to achieve high-precision adjustment of the output power of the radio frequency signal of the radio frequency equipment. In the embodiment shown in the accompanying drawings, the output control method includes the following steps: S101 . In response to a first control signal, a power supply voltage of a radio frequency device is stepped down to obtain an output voltage VOUT.

[0011] In this step, the first control signal is generated according to the preset output power and output current of the radio frequency device. In the present invention, the first control signal may include a voltage signal, and the voltage signal is generated according to the difference between the preset output power and the actual output power corresponding to the output current, that is, it can be generated according to the preset output power and the actual output current of the radio frequency device.

[0012] Specifically, this step includes: obtaining a reference voltage, and stepping down the power supply voltage of the radio frequency device according to the voltage of the first control signal and the reference voltage to obtain the output voltage VOUT. In this embodiment, the step-down regulation can be performed by a half-bridge BUCK step-down circuit, that is, a PWM control signal can be output according to the voltage signal of the first control signal and the reference voltage to control the half-bridge BUCK step-down circuit connected to the power supply of the radio frequency device to work, thereby stepping down the power supply voltage of the radio frequency device to obtain the output voltage VOUT.

[0013] That is, in this embodiment, the power supply voltage of the radio frequency device is adjusted to a large extent through the half-bridge BUCK buck circuit according to the first control signal, so that the output voltage VOUT after buck adjustment is close to the voltage corresponding to the preset output power.

[0014] Furthermore, in some embodiments, this step may also include: sampling the output voltage after the half-bridge BUCK buck circuit has stepped down to obtain a sampled output voltage; performing differential amplification processing on the sampled output voltage and the voltage of the first control signal to obtain a feedback voltage signal; outputting a PWM control signal according to the feedback voltage signal and the reference voltage to control the operation of the half-bridge BUCK buck circuit, thereby performing feedback regulation on the output voltage to obtain the output voltage VOUT. In this embodiment, the voltage of the first control signal generated according to the preset output power and the output voltage after the initial step-down regulation can be differentially amplified, so that the initial output voltage can be feedback regulated to obtain the output voltage VOUT, so as to obtain a more accurate output voltage, that is, the value of the output voltage after feedback regulation is closer to the voltage value corresponding to the preset output power.

[0015] S102: Sample the output current to obtain a sampled current.

[0016] In this step, the output current finally output to the load is sampled to obtain the sampled current, so that the actual output power at this time can be known, and the actual output power POUT1 can be obtained according to the formula POUT1=I²R, where I is the sampled current and R is the load impedance. It can be understood that the output current described in step S101 is actually the sampled current.

[0017] S103 , generating a second control signal with adjustable signal frequency dead time according to the sampled current.

[0018] In this step, the second control signal is a bidirectional symmetrical square wave signal with adjustable signal frequency dead time. The signal frequency dead time can be pre-set according to the preset output power of the RF device. During the adjustment process, the adjustment setting can be made according to the difference between the actual output power corresponding to the sampling current and the preset output power. Then, in this step, the second control signal with adjustable signal frequency dead time can be generated according to the difference between the preset output power and the actual output power corresponding to the sampling current.

[0019] S104 , controlling the full-bridge circuit in response to the second control signal with adjustable signal frequency dead time, so as to fine-tune the pulse width of the output voltage VOUT to obtain actual output.

[0020] like Figure 2 As shown, usually, the frequency of the RF signal is generated by the bidirectional symmetrical square wave frequency Determine, where t1 and t2 are the full-bridge opening time, and in the present invention, the second control signal generated is a bidirectional symmetrical square wave signal with adjustable signal frequency dead time, then its frequency is , where t3 and t5 are the adjustable dead zone times.

[0021] It can be understood that, under the condition that the output voltage VOUT and the frequency f2 are fixed after the step-down regulation, the increase of the dead time t3 and t5 in one cycle will cause the output working time (i.e., the opening time) t4 and t6 to decrease, that is, the RF output power under this condition will be reduced. At the same time, in order to prevent the excessive dead time adjustment time from causing the energy storage energy of the transformer to be exhausted and become a waveform-free output, thereby making the output waveform discontinuous and the waveform seriously deformed, preferably, in this embodiment, the dead time of the second control signal in one frequency cycle can account for 0%≤t3=t5≤10%, that is, the upper limit of the dead time adjustable time t3 and t5 is limited to 10%, then the full-bridge opening time t4 and t6 in one frequency cycle account for 40%≤t4=t6≤50%, and t3+t4=t5+t6, and when the frequency f1=f2, t1=t3+t4, t2=t5+t6.

[0022] For example, if the error between the value of the actual output power POUT1 and the value of the preset output power P1 is greater than 10%, that is, if POUT1>110%*P1, the f2 frequency dead time t3 and t5 are increased; if POUT1<90%*P1, the f2 frequency dead time t3 and t5 are reduced; and if the error is within 10%, that is, when 90%*P1≤POUT1≤110%*P1, the f2 frequency dead time t3 and t5 are not adjusted, and it is considered that the value of the actual output power POUT1 of the radio frequency device is closest to the value of P1 at this time, and it will be recognized that the preset output power is reached. That is, in this embodiment, the value of the actual output power POUT1 and the preset output power within 10% of the error will be recognized as reaching the preset output power.

[0023] S105, amplifying the actual output and outputting it to the load, so that the actual output power output by the radio frequency device to the load reaches the preset output power.

[0024] In this embodiment, the power amplification factor may be 1, or may be set according to actual needs.

[0025] Preferably, in some other embodiments, after the actual output is amplified and then output to the load, the method may further include: sampling the output current to obtain the sampled current at this time, and outputting the first control signal and / or the second control signal according to the sampled current to adjust the actual output power of the RF device. That is, in this embodiment, if the actual output power deviates from the preset output power due to the RF device itself during the operation of the RF device, further adjustment may be performed. During the adjustment process, the first control signal and the second control signal may be generated according to the preset output power and the sampled current of the RF device. Understandably, the voltage of the first control signal may be adjusted according to the difference between the sampled current obtained by sampling and the voltage corresponding to the preset output power, and / or the signal frequency dead time of the second control signal may be adjusted to make further adjustments, that is, the voltage of the first control signal or the signal frequency dead time of the second control signal may be adjusted separately to adjust the output power, or the output power may be adjusted jointly by adjusting the voltage of the first control signal in combination with the signal frequency dead time of the second control signal, so that the adjustment is more flexible and has higher adjustment accuracy. For example: if the gap is relatively small, it is preferred to precisely fine-tune the error by adjusting only the signal frequency dead time of the second control signal. If the gap is relatively large, it can be adjusted by adjusting the voltage of the first control signal and then adjusting the signal frequency dead time of the second control signal. Alternatively, it is also possible to adjust only the voltage of the first control signal.

[0026] When the output control method of the present invention is applied to the operation of a radio frequency device, first, the user can set a preset output power P1, and can also preset a signal frequency dead time of a second control signal (for example, the duty cycle can be preset to 5%), output a first control signal according to the preset output power and output current, and step down the power supply voltage of the radio frequency device in response to the first control signal to obtain an output voltage VOUT. At this time, the full-bridge circuit is turned on according to the original turn-on time, and the preset signal frequency dead time is not changed. The output current at this time is sampled, and a second control signal with an adjusted signal frequency dead time is generated according to the difference between the actual output power and the preset output power and sent to the full-bridge circuit, so as to change the turn-on time of the full-bridge circuit within one cycle, thereby fine-tuning the pulse width of the output voltage VOUT, thereby achieving fine-tuning of the actual output power, and power amplification can also be performed, so that the actual output power of the radio frequency device reaches the preset output power.

[0027] Reference Figure 3 to Figure 4 , Figure 3 to Figure 4A specific embodiment of the output control circuit of the present invention is shown. The output control circuit can be applied to radio frequency devices such as radio frequency therapeutic devices to achieve high-precision adjustment of the output power of the radio frequency signal of the radio frequency device. In the embodiment shown in the accompanying drawings, the output control circuit includes a programmable voltage regulation circuit 10, a full-bridge circuit 20, a transformer T1, an isolation sampling circuit 60 and a main control circuit 30; wherein the programmable voltage regulation circuit 10 is connected to the power supply VIN of the radio frequency device, and is used to step down and regulate the power supply voltage VIN of the radio frequency device in response to a first control signal from the main control circuit 30 to obtain an output voltage; the full-bridge circuit 20 is connected to the output end of the programmable voltage regulation circuit 10, and is used to control the conduction of the electronic switch of the full-bridge circuit 20 within one cycle in response to a second control signal with adjustable signal frequency dead time from the main control circuit 30, that is, to control the opening time of the switch tube within one cycle of the full-bridge circuit 20, thereby adjusting the pulse of the output voltage from the programmable voltage regulation circuit 10 The width is fine-tuned to obtain the actual output; the transformer T1 is connected between the output end of the full-bridge circuit 20 and the load, and is used to amplify the actual output and output it to the load, so that the output power corresponding to the actual output of the RF device to the load reaches the preset output power; the input end of the isolated sampling circuit 60 is connected to the output end of the transformer T1, and is used to collect the output current of the secondary side of the transformer to obtain the sampling current; the main control circuit 30 is connected to the programmable voltage regulating circuit 10, the full-bridge circuit 20 and the isolated sampling circuit 60, and is used to output the first control signal and / or the second control signal according to the preset output power and the collected sampling current, so as to control the operation of the programmable voltage regulating circuit 10 and the full-bridge circuit 20, thereby adjusting the actual output power of the RF device. In the present invention, the first control signal may include a voltage signal, which is generated according to the difference between the preset output power and the actual output power corresponding to the sampling current. The second control signal is a bidirectional symmetrical square wave signal with an adjustable signal frequency dead time. In addition to being generated according to the preset output power of the radio frequency device, the first control signal and the second control signal can also be generated by adjusting according to the sampling current. In the actual adjustment process, the present invention can use the programmable voltage regulating circuit 10 or the full-bridge circuit 20 alone to adjust the power of the radio frequency signal (that is, the output power of the radio frequency device), and can also use the programmable voltage regulating circuit 10 and the full-bridge circuit 20 to jointly adjust the power of the radio frequency signal. The adjustment is more flexible, the power adjustment range is wider, and the output power adjustment accuracy is higher.

[0028] Preferably, if Figure 4As shown, in this embodiment, the programmable voltage regulation circuit 10 includes a DC-DC power supply chip U200, a half-bridge BUCK buck circuit and a differential amplifier circuit 14, wherein the half-bridge BUCK buck circuit includes a half-bridge driver chip U201 and a BUCK circuit 122, the input pin of the half-bridge driver chip U201 is connected to the output end of the DC-DC power supply chip U200, and its output pin is connected to the control end of the switch tube in the BUCK circuit 122, the input end of the BUCK circuit 122 is connected to the power supply VIN of the radio frequency device, and its output end is connected to the differential amplifier circuit 14 and the full-bridge circuit 20, which is used to step down and regulate the power supply voltage VIN of the radio frequency device; the differential amplifier circuit 14 includes a differential amplifier U20, the non-inverting input end of the differential amplifier U20 is connected to the output end of the BUCK circuit 122 through a second resistor divider circuit 13 (composed of a resistor R222, a resistor R225 and a resistor R229), and its inverting input The first end is connected to the main control circuit 30, the output end of the differential amplifier U20 is connected to the input end of the DC-DC power chip U200, and is used to output a feedback voltage signal to the DC-DC power chip U200 according to the voltage of the first control signal and the output voltage of the BUCK circuit 122; the second in-phase input end of the DC-DC power chip U200 is connected to the output end of the differential amplifier U20, and its second inverting input end is connected to the reference voltage VREF through a first resistor voltage divider circuit (composed of a resistor R200 and a resistor R213). In this embodiment, the reference voltage VREF is the voltage at the output end of the 5V reference regulator inside the DC-DC power chip U200. The output end of the DC-DC power chip U200 is connected to the half-bridge BUCK buck circuit, and is used to output a PWM control signal according to the feedback voltage signal and the reference voltage VREF to control the operation of the half-bridge BUCK buck circuit, thereby performing feedback regulation on the output voltage to obtain the output voltage VOUT. Preferably, in this embodiment, the main control circuit 30 includes an MCU 31, and the MCU 31 is connected to the differential amplifier circuit 14 and the full-bridge circuit 20. The full-bridge circuit 20 is a full-bridge circuit composed of four electronic switches. The electronic switches usually use MOSFET tubes, and two MOSFET tubes form a bridge arm. The midpoint of the bridge arm is the output end of the full-bridge circuit 20. Since the full-bridge circuit 20 is well known to those skilled in the art, it will not be described here. The model of the DC-DC power chip U200 can be TL494, and the model of the half-bridge driver chip U201 can be IR2014. In some other embodiments, the DC-DC power chip U200 and the half-bridge driver chip U201 can respectively use chips of other models but can achieve the above functions.

[0029] In this embodiment, the differential amplifier circuit 14 further includes a first voltage follower U21 and a second voltage follower U22, the non-inverting input terminal of the first voltage follower U21 is connected to the output terminal of the second resistor voltage divider circuit 13, the output terminal of the first voltage follower U21 is connected to its inverting input terminal, and is connected to the non-inverting input terminal of the differential amplifier U20, the non-inverting input terminal is connected to the main control circuit 30 through a resistor R230, the output terminal of the second voltage follower U22 is connected to its inverting input terminal, and is connected to the inverting input terminal of the differential amplifier U20. Preferably, the resistance values ​​of the resistors R216, R217, and R218 at the non-inverting input terminal of the differential amplifier U20 are respectively the same as the resistance values ​​of the resistors R226, R227, and R228 at the inverting input terminal thereof.

[0030] Specifically, Figure 4 As shown, the BUCK circuit 122 includes a switch tube Q201, a switch tube Q203, a switch tube Q200, a switch tube Q202, a diode D201, a diode D202, a resistor R204, a resistor R214, an inductor L200 and a filter capacitor CE200. In this embodiment, the filter capacitor CE200 can preferably be a capacitor group composed of multiple capacitors connected in parallel. The input end of the switch tube Q200 is connected to the power supply VIN of the radio frequency device, and the control end thereof is connected to the cathode of the diode D201, the input end of the switch tube Q201 and one end of the resistor R204. The output ends of the switch tube Q200 and the switch tube Q201 and the other end of the resistor R204 are all connected to the input end of the switch tube Q202 and one end of the inductor L200. The control end of the switch tube Q202 is connected to the cathode of the diode D202, the input end of the switch tube Q203 and one end of the resistor R214. The anode of the diode D201 and the output end of the switch tube Q201 are connected to the cathode of the diode D202, the input end of the switch tube Q203 and one end of the resistor R214. The control end is connected, and is connected to the high-end gate driver output pin of the half-bridge driver chip U201 through a resistor R207, the positive electrode of the diode D202 is connected to the control end of the switch tube Q203, and is connected to the low-end gate driver output pin of the half-bridge driver chip U201 through a resistor R212, the other end of the inductor L200 is connected to one end of the filter capacitor CE200, and serves as the output end of the BUCK circuit 122, and the other end of the filter capacitor CE200 and the resistor R214, the output end of the switch tube Q203 and the switch tube Q202 are all grounded. Preferably, in this embodiment, the switch tube Q201 and the switch tube Q203 use PNP type triodes, and the base, emitter and collector of the PNP type triode serve as their control end, input end and output end respectively; and the switch tube Q200 and the switch tube Q202 use NMOS tubes, and the gate G, drain D and source S of the NMOS tube serve as their control end, input end and output end respectively.

[0031] It can be understood that when the programmable voltage regulating circuit 10 described in this embodiment is working, the DC-DC power supply chip U200 of model TL494 serves as the control chip of the programmable voltage regulating circuit 10, and the output pin (pin 9) of the DC-DC power supply chip U200 outputs a signal to control the half-bridge driver chip U201, and the output voltage VOUT is output after passing through the BUCK circuit 122. After the voltage is divided and sampled by the second resistor voltage divider circuit 13, the VDAC voltage signal of the first control signal (DAC control signal) output by the MCU 31 passes through the first voltage follower U21 and the second voltage follower U22 respectively, and is connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier U20 for differential amplification processing, and then the feedback voltage signal is output to the second non-inverting input terminal of the DC-DC power supply chip U200. At this time, the voltage at the second non-inverting input terminal is the voltage of the feedback voltage signal. , while the voltage at its second inverting input , the voltages of the second in-phase input terminal and the second inverting input terminal are compared by the internal operational amplifier comparator of the DC-DC power supply chip U200, and the output pin thereof outputs a PWM control signal, and the PWM control signal is given to the half-bridge driver chip U201 to control the opening time of the upper bridge and the lower bridge thereof, thereby performing closed-loop regulation on VOUT; further, according to the virtual short property of the operational amplifier, it can be known that VFB will eventually be equal to V2IN, and if the resistance parameters in the first resistor voltage divider circuit (composed of resistor R200 and resistor R213) are selected, V2IN is a fixed value, that is, VFB is a fixed value, and then according to the above VFB calculation formula, it can be known that when VDAC increases, VOUT will also increase accordingly, and when VDAC decreases, VOUT will also decrease accordingly, and VOUT can be controlled by VDAC, that is, the output voltage of the programmable voltage regulation circuit 10 can be controlled by the first control signal from the MCU 31, thereby realizing the intensity regulation of the output power.

[0032] Furthermore, the output control circuit also includes a primary filter circuit 40, a secondary filter circuit 50 and a current transformer T2. The primary filter circuit 40 is composed of a capacitor C1 and a capacitor C2 connected in series, and is connected between the two output ends of the full-bridge circuit 20. The two ends of the primary side of the transformer T1 are connected to the two output ends of the full-bridge circuit 20. The secondary filter circuit 50 includes a capacitor C3, which is connected to the secondary side of the transformer T1, and the same-name end of the secondary side of the transformer T1 is connected to one end of the load through a coupling capacitor C. The opposite-name end and the same-name end of the primary side of the current transformer T2 are respectively connected to the opposite-name end of the secondary side of the transformer T1 and the other end of the load. The secondary side of the current transformer T2 is connected to the input end of the isolation sampling circuit 60. Preferably, in this embodiment, Figure 3As shown, the transformer T1 is a three-winding high-frequency transformer T1, and a tap is led out from the secondary side of the transformer T1. The same-name terminals of the secondary side can be connected to a load through a coupling capacitor C, respectively. The load can be a capacitive load C-LOAD or a resistive load R-LOAD. It can be understood that the isolation sampling circuit 60 adopts an isolation sampling circuit 60 commonly used by those skilled in the art, for example, an isolation sampling circuit composed of an isolation operational amplifier can be adopted, and its specific structure is well known to those skilled in the art and will not be repeated here.

[0033] The working process of the output control circuit of the present invention applied to the radio frequency device is as follows: when the radio frequency device is initially turned on, the programmable voltage regulating circuit 10 can output the lowest voltage, the MCU 31 generates a second control signal with an adjustable signal frequency dead time and generates a radio frequency signal of a corresponding frequency through the full-bridge circuit 20 and the transformer T1, and then the output control circuit of the present invention officially starts to work, the MCU 31 generates a first control signal according to the preset output power and output current, the programmable voltage regulating circuit 10 preliminarily adjusts the output voltage according to the first control signal, at this time the signal frequency dead time of the second control signal can be temporarily unchanged, the isolation sampling circuit 60 samples the output current on the secondary side of the transformer T1, and the sampled current obtained at this time is fed back to the MCU 31, MCU31 then adjusts the signal frequency dead time of the second control signal to control the opening time of the full-bridge circuit 20 within one cycle, thereby fine-tuning the pulse width of the output voltage, so that the corresponding actual output power at this time is accurately adjusted to the preset output power. In the above adjustment process, the dead time adjustment range of the second control signal can be narrowed to 0%-10%. Large-scale voltage regulation is mainly achieved by the programmable voltage regulation circuit 10. The full-bridge circuit 20 based on the signal frequency dead time adjustment is mainly used for accurate error repair. Further, in order to avoid some unexpected situations, the isolation sampling circuit 60 can also sample the sampled current output to the load after fine-tuning the full-bridge circuit 20, and adjust the first control signal and / or the second control signal according to the difference between the actual output power corresponding to the sampled current at this time and the preset output power, and make further adjustments.

[0034] The present invention also provides a radio frequency device, the radio frequency device includes the output control circuit described in the above embodiment, so as to adjust the power supply voltage of the radio frequency device to a large extent according to the first control signal through the programmable voltage regulation circuit, and then control the opening time of the full-bridge circuit within one cycle according to the second control signal with adjustable signal frequency dead time, so as to fine-tune the pulse width of the output voltage through the full-bridge circuit, that is, to accurately repair the error between the preset output power and the actual output power, so as to achieve high-precision adjustment of the output power of the radio frequency device, and the adjustable range of the signal frequency dead time can be narrow, so as to solve the problem that the waveform is seriously deformed and distorted after amplification due to the large proportion of dead time. It can be understood that the output control method described in the above embodiment can be applied to the radio frequency device including the output control circuit described in the above embodiment, and the output power of the radio frequency device is adjusted by the output control circuit, and the adjustment accuracy is relatively high.

[0035] The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form.

[0036] Those skilled in the art may make various equivalent changes and improvements based on the above embodiments. All equivalent changes or modifications made within the scope of the claims should fall within the protection scope of the present invention.

Claims

1. An output control method, applied to a radio frequency device, characterized in that: The output control method comprises: In response to a first control signal, a power supply voltage of the radio frequency device is stepped down to obtain an output voltage VOUT, wherein the first control signal is generated according to a preset output power and output current of the radio frequency device; Sampling the output current to obtain a sampling current; Generate a second control signal with adjustable signal frequency dead time according to the sampled current; In response to a second control signal with an adjustable signal frequency dead time, the full-bridge circuit is controlled to fine-tune the pulse width of the output voltage VOUT to obtain an actual output; The actual output is power-amplified and then output to the load, so that the actual output power output by the RF device to the load reaches the preset output power.

2. The output control method according to claim 1, characterized in that: The step of stepping down the power supply voltage of the radio frequency device in response to the first control signal to obtain the output voltage VOUT specifically includes: Obtaining a reference voltage, and stepping down and regulating the power supply voltage of the radio frequency device according to the voltage of the first control signal and the reference voltage; Sampling the output voltage after the step-down regulation to obtain a sampled output voltage; Performing differential amplification processing on the sampled output voltage and the voltage of the first control signal to obtain a feedback voltage signal; The output voltage is feedback-regulated according to the feedback voltage signal and the reference voltage to obtain the output voltage VOUT.

3. The output control method according to claim 1, characterized in that: After the actual output is power-amplified and then outputted to the load, the method further includes: sampling the output current to obtain a sampled current, and outputting the first control signal and / or the second control signal according to the sampled current to adjust the actual output power of the radio frequency device.

4. An output control circuit, applied to radio frequency equipment, characterized in that: The output control circuit includes a program-controlled voltage regulation circuit, a full-bridge circuit, a transformer, an isolation sampling circuit and a main control circuit; wherein, The program-controlled voltage regulating circuit is connected to the power supply of the radio frequency device, and is used to step down and regulate the power supply voltage of the radio frequency device in response to the first control signal from the main control circuit to obtain an output voltage; The full-bridge circuit is connected to the output end of the program-controlled voltage regulation circuit, and is used to control the on-time of the full-bridge circuit within one cycle in response to the second control signal with adjustable dead time of the signal frequency from the main control circuit, so as to fine-tune the pulse width of the output voltage from the program-controlled voltage regulation circuit to obtain the actual output; The transformer is connected between the output end of the full-bridge circuit and the load, and is used to amplify the actual output and output it to the load, so that the actual output power output by the radio frequency device to the load reaches the preset output power; The input end of the isolation sampling circuit is connected to the output end of the transformer, and is used to collect the output current of the secondary side of the transformer to obtain the sampling current; The main control circuit is connected to the programmable voltage regulating circuit, the full-bridge circuit and the isolated sampling circuit, and is used to output a first control signal and / or a second control signal according to a preset output power and a collected sampling current to control the operation of the programmable voltage regulating circuit and the full-bridge circuit, thereby adjusting the actual output power of the radio frequency device.

5. The output control circuit according to claim 4, characterized in that: The program-controlled voltage regulation circuit includes a DC-DC power supply chip and a half-bridge BUCK step-down circuit, wherein: The half-bridge BUCK buck circuit comprises a half-bridge driver chip and a BUCK circuit, wherein the input pin of the half-bridge driver chip is connected to the output end of the DC-DC power chip, and the output pin thereof is connected to the control end of the switch tube in the BUCK circuit, the input end of the BUCK circuit is connected to the power supply of the radio frequency device, and the output end thereof is connected to the full-bridge circuit, so as to buck the power supply voltage of the radio frequency device; The second in-phase input terminal of the DC-DC power supply chip is connected to the main control circuit, the second inverting input terminal of the DC-DC power supply chip is connected to the reference voltage through a first resistor voltage divider circuit, and the output terminal of the DC-DC power supply chip is connected to the half-bridge BUCK buck circuit, which is used to adjust the output voltage of the half-bridge BUCK buck circuit according to the voltage of the first control signal and the reference voltage.

6. The output control circuit according to claim 5, characterized in that: The program-controlled voltage regulation circuit also includes a differential amplifier circuit, wherein: The differential amplifier circuit includes a differential amplifier, a non-inverting input terminal of the differential amplifier is connected to the output terminal of the BUCK circuit through a second resistor voltage divider circuit, and an inverting input terminal thereof is connected to the main control circuit. The output terminal of the differential amplifier is connected to the second non-inverting input terminal of the DC-DC power supply chip, and is used to output a feedback voltage signal to the DC-DC power supply chip according to the voltage of the first control signal and the output voltage of the BUCK circuit, so that the DC-DC power supply chip outputs a PWM control signal according to the feedback voltage signal and the reference voltage, controls the operation of the half-bridge BUCK buck circuit, and thereby performs feedback regulation on the output voltage.

7. The output control circuit according to claim 6, characterized in that: The differential amplifier circuit also includes a first voltage follower and a second voltage follower, the non-inverting input terminal of the first voltage follower is connected to the output terminal of the second resistor voltage divider circuit, the output terminal of the first voltage follower is connected to its inverting input terminal and connected to the non-inverting input terminal of the differential amplifier, the non-inverting input terminal of the second voltage follower is connected to the main control circuit via a resistor R230, and the output terminal of the second voltage follower is connected to its inverting input terminal and connected to the inverting input terminal of the differential amplifier.

8. The output control circuit according to claim 5, characterized in that: The BUCK circuit includes a switch tube Q201, a switch tube Q203, a switch tube Q200, a switch tube Q202, a diode D201, a diode D202, a resistor R204, a resistor R214, an inductor and a filter capacitor, wherein the input end of the switch tube Q200 is connected to the power supply of the radio frequency device, and its control end is connected to the cathode of the diode D201, the input end of the switch tube Q201 and one end of the resistor R204, the output ends of the switch tube Q200 and the switch tube Q201 and the other end of the resistor R204 are all connected to the input end of the switch tube Q202 and one end of the inductor, and the control end of the switch tube Q202 is connected to the diode D2 The cathode of the diode D201 is connected to the control end of the switch Q201, and is connected to the high-end gate driver output pin of the half-bridge driver chip through a resistor R207. The anode of the diode D202 is connected to the control end of the switch Q203, and is connected to the low-end gate driver output pin of the half-bridge driver chip through a resistor R212. The other end of the inductor is connected to one end of the filter capacitor and serves as the output end of the BUCK circuit. The other ends of the filter capacitor and the resistor R214, the output ends of the switch Q203 and the switch Q202 are all grounded.

9. The output control circuit according to claim 4, characterized in that: The output control circuit also includes a primary filter circuit, a secondary filter circuit and a current transformer. The primary filter circuit is connected between the two output ends of the full-bridge circuit. The two ends of the primary side of the transformer are connected to the two output ends of the full-bridge circuit. The secondary filter circuit is connected to the secondary side of the transformer, and the same-name end of the secondary side of the transformer is connected to one end of the load through a coupling capacitor. The opposite-name end and the same-name end of the primary side of the current transformer are respectively connected to the opposite-name end of the secondary side of the transformer and the other end of the load. The secondary side of the current transformer is connected to the input end of the isolation sampling circuit.

10. A radio frequency device, characterized in that: The output control circuit comprises any one of claims 4 to 9.

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